1.\" Copyright (c) 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)vis.1 8.1 (Berkeley) 06/06/93 7.\" 8.Dd 9.Dt VIS 1 10.Os BSD 4.4 11.Sh NAME 12.Nm vis 13.Nd display non-printable characters in a visual format 14.Sh SYNOPSIS 15.Nm vis 16.Op Fl cbflnostw 17.Op Fl F Ar foldwidth 18.Op Ar file ... 19.Sh DESCRIPTION 20.Nm Vis 21is a filter for converting non-printable characters 22into a visual representation. It differs from 23.Ql cat -v 24in that 25the form is unique and invertible. By default, all non-graphic 26characters except space, tab, and newline are encoded. 27A detailed description of the 28various visual formats is given in 29.Xr vis 3 . 30.Pp 31Options supported by 32.Nm vis : 33.Bl -tag -width Ds 34.It Fl b 35Turns off prepending of backslash before up-arrow control sequences 36and meta characters, and disables the doubling of backslashes. This 37produces output which is neither invertible or precise, but does 38represent a minimum of change to the input. It is similar to 39.Dq Li cat -v . 40.It Fl c 41Request a format which displays a small subset of the 42non-printable characters using C-style backslash sequences. 43.It Fl F 44Causes 45.Nm vis 46to fold output lines to foldwidth columns (default 80), like 47.Xr fold 1 , 48except 49that a hidden newline sequence is used, (which is removed 50when inverting the file back to its original form with 51.Xr unvis 1 ) . 52If the last character in the encoded file does not end in a newline, 53a hidden newline sequence is appended to the output. 54This makes 55the output usuable with various editors and other utilities which 56typically don't work with partial lines. 57.It Fl f 58Same as 59.Fl F . 60.It Fl l 61Mark newlines with the visable sequence 62.Ql \e$ , 63followed by the newline. 64.It Fl n 65Turns off any encoding, except for the fact that backslashes are 66still doubled and hidden newline sequences inserted if 67.Fl f 68or 69.Fl F 70is selected. When combined with the 71.Fl f 72flag, 73.Nm vis 74becomes like 75an invertible version of the 76.Xr fold 1 77utility. That is, the output 78can be unfolded by running the output through 79.It Fl o 80Request a format which displays non-printable characters as 81an octal number, \eddd. 82.It Fl s 83Only characters considered unsafe to send to a terminal are encoded. 84This flag allows backspace, bell, and carriage return in addition 85to the default space, tab and newline. 86.Xr unvis 1 . 87.It Fl t 88Tabs are also encoded. 89.It Fl w 90White space (space-tab-newline) is also encoded. 91.El 92.Sh SEE ALSO 93.Xr unvis 1 94.Xr vis 3 95.Sh HISTORY 96The 97.Nm 98command appears in 99.Bx 4.4 . 100